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(svn r22302) -Codechange: Replace a linear search with a binary search.

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frosch 2011-04-09 11:32:11 +00:00
parent 1e64012e9f
commit ecb3701210
1 changed files with 12 additions and 1 deletions
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13
src/blitter/base.cpp
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@ -50,8 +50,19 @@ void Blitter::DrawLine(void *video, int x, int y, int x2, int y2, int screen_wid
int frac_diff = width * max(dx, dy);
if (width > 1) {
/* compute frac_diff = width * sqrt(dx*dx + dy*dy)
* Start interval:
* max(dx, dy) <= sqrt(dx*dx + dy*dy) <= sqrt(2) * max(dx, dy) <= 3/2 * max(dx, dy) */
int frac_sq = width * width * (dx * dx + dy * dy);
while (frac_diff * frac_diff < frac_sq) frac_diff++;
int frac_max = 3 * frac_diff / 2;
while (frac_diff < frac_max) {
int frac_test = (frac_diff + frac_max) / 2;
if (frac_test * frac_test < frac_sq) {
frac_diff = frac_test + 1;
} else {
frac_max = frac_test - 1;
}
}
}
if (dx > dy) {